As one of technologies to increase the communication speed of mobile stations located at cell edges, DC-HSDPA using existing HSDPA (High Speed Downlink Packet Access) has been examined in 3GPP (3rd Generation Partnership Project). DC-HSDPA uses two frequency channels (each of which is 5 MHz) contained in the same frequency band in order to increase the downlink speed. The general idea of DC-HSDPA, which has been currently examined in 3GPP, is explained hereinafter. Note that the details of DC-HSDPA technique, which has been currently proposed, are explained in Non-patent literatures 1 to 3 mentioned below.
In DC-HSDPA, a second serving HS-DSCH cell is referred to as “secondary-serving HS-DSCH cell”. Meanwhile, a first serving HS-DSCH cell is simply referred to as “serving HS-DSCH cell”. A secondary-serving HS-DSCH cell is dependently formed on condition that a serving HS-DSCH cell is already generated. Note that the serving HS-DSCH cell may be also referred to as “primary carrier” or “base carrier”. Meanwhile, the secondary-serving HS-DSCH cell may be also referred to as “secondary carrier” or “extended carrier”.
In this specification, in order to clearly distinguish between these two serving HS-DSCH cells, the first serving HS-DSCH cell is referred to as “primary-serving HS-DSCH cell”. Further, in the following explanation, the primary-serving HS-DSCH cell and the secondary-serving HS-DSCH cell may be also referred as simply “primary cell” and “secondary cell” respectively.
FIG. 22 shows physical channels used to perform packet communication with DC-HSDPA between a base station (Node B) 91 supporting DC-HSDPA and a mobile station 92. HS-PDSCH is a downlink physical channel for data transmission, and transfers a transport channel HS-DSCH. HS-SCCH is used for transmission of downlink signaling information about HS-DSCH transfer. HS-DPCCH is an uplink physical channel used to transmit, from the mobile station 92 to the base station 91, feedback information about HS-DSCH transfer. This feedback information includes an ACK response regarding a hybrid ARQ (Automatic repeat-request), and a CQI (channel Quality Indication). The uplink DPCH and downlink DPCH are used to transmit/receive control information about DC-HSDPA. Needless to say, other common physical channels indispensable to the generation of primary and secondary cells (such as P-CPICH, SCH, P-CCPCH and S-CCPCH) are also used. The formal names of these physical channels and transport channels, which are shown above in abbreviated names, are shown below.
P-CPICH: Primary Common Pilot Channel
DPCH: Dedicated Physical Channel
HS-DPCCH: Dedicated Physical Control Channel (uplink) for HS-DSCH
HS-DSCH: High Speed Downlink Shared Channel
HS-PDSCH: High Speed Physical Downlink Shared Channel
HS-SCCH: Shared Control Channel for HS-DSCH
P-CCPCH: Primary Common Control Physical Channel
S-CCPCH: Secondary Common Control Physical Channel
SCH: Synchronisation Channel
When two serving HS-DSCH cells are established in a base station supporting DC-HSDPA, the activation and deactivation of the secondary-serving HS-DSCH cell are controlled by the base station. A command (HS-SCCH Oder) that is used by the base station to instruct a mobile station (UE) on the activation and deactivation of the secondary-serving HS-DSCH cell is transmitted to the mobile station by using HS-SCCH, which is a downlink control channel.
Meanwhile, as the indoor voice communication and data transmission have grown in demand owing to the widespread use of mobile phones, the development of compact base stations that can be installed in user's houses, offices, and the likes has been under way. These compact base stations are installed in houses, small-scale offices, and the likes by the owners of the compact base stations, for example, and are connected to an upper layer apparatus on core-network sides by using ADSLs (Asymmetric Digital Subscriber Lines) or fiber-optic lines. In 3GPP, the standardization task has been under way while defining these compact base stations as “Home NodeB” and “Home eNodeB” (for example, see Non-patent literature 4). Note that “Home NodeB” is a compact base station for use in UMTS (Universal Mobile Telecommunications System), while the “Home eNodeB” is a compact base station for use in LTE (Long Term Evolution). In this specification, these compact base stations are referred to as “home base stations”, and cells generated by these home base stations are referred to as “home cells”.